The Railway gun the Germans used to shell Paris in WWII
The Potato Gun
The Germans, particularly in Rommel's area - Normandy, had many strong bunkers and gun emplacements. Erwin Rommel was greatly in favor of strengthening the coast.
The British used a multitude of weapons. Individual soldiers carried the Lee-Enfield .303 rifle, the Bren squad machine gun, the Thompson machine gun, and some varied pistols. The PIAT anti tank launcher and the Mills Grenade were also used.
The Paris gun made by the Germans in WWI.
The Germans used the PanzerFaust (tank fist). It was a disposable anti tank weapon.
MP40 submachine gun by the germans Thompson by the americans ppsh-41 by the russians
Captive Bolt Gun
Tin is not used in present day gun metal.
Black Powder.
Schwerer Gustav and Dora were the names of two huge German railway guns of diameter 80 cm K (E). They were used on the Russian front in the Crimea. Both were destroyed at the end of the war. A smaller railroad gun, "Anzio Annie" is at Aberdeen Proving Ground, Maryland. It was used by the Germans at the siege of Anzio, Italy and was captured and restored.
The Germans and the Austrians were the first to employ the use of the Maxim machine gun in 1914. The British played catch up in this weapon, but soon had thousands of them in the field.